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Conference Presentations by Abdullah Kaymakci

ASME 2018 Joint Rail Conference, 2018

ASME 2018 Joint Rail Conference, 2018

2017 International Conference on the Industrial and Commercial Use of Energy (ICUE), 2017

The production of greenhouse gases (GHG) has led to the Earth’s surface temperature increasing by... more The production of greenhouse gases (GHG) has led to the Earth’s surface temperature increasing by an average of 0.6oC in the 20th century. This is partly due to over reliance on fossil fuels. Human activities are estimated to account for about 69% of GHG emissions. There is now an urgent need for alternative fuels, especially renewables such as biomass, to mitigate this. In most of Sub-Saharan Africa, cooking is conducted in open fires using fire wood. This practice has poor health implications due to gases emitted largely due to incomplete combustion. The consequence is reduced mortality especially for women and children due to respiratory related diseases such as chronic obstruction pulmonary disease (COPD). The main aim of this work is to report on tests conducted on a low-cost biomass briquette domestic stove that was developed to improved biomass briquette combustion. Thermal efficiency, rate of heat loss and combustion effectiveness of the design was analysed as key performance variables of the stove. The goal was to develop a safe and reliable low-cost biomass briquette stove that will be used for domestic cooking in communities with low-income streams. Stove geometry and temperatures at various points were identified as major contributors to stove effectiveness. During the investigation, controlled cooking test (CCT) method was used. Results showed good stove performance for typical cooking times.

P91 and 10CrMo9-10 creep resistant steels are critical to the performance of boiler tubes and pow... more P91 and 10CrMo9-10 creep resistant steels are critical to the performance of boiler tubes and power generating plants in general. Components made from these materials are mainly joined by welding. This paper reports on the comparative study of the effect of TIG and SMAW welding on the mechanical performance of P91 and 10CrMo9-10. TIG was used for root welding while SMAW was used for weld filling of V-butt joints. Specimens of the two alloys prepared using recommended welding procedures are evaluated using optical microscopy and Vickers micro hardness assessment. Some specimens were post weld heat treated while others were not. Post weld heat treated (PWHT) specimens exhibited similar properties as the corresponding base materials for both steels. TIG welding resulted in significant grain size reduction in both steels. PWHT produced more consistent grain structure, which is favorable.

This paper presents a study on the influence of manufacturing conditions on the fatigue life of w... more This paper presents a study on the influence of manufacturing conditions on the fatigue life of welded joints of high strength steels P355NL-1 and P355NL-2. Welding conditions were varied by adjusting the welding parameters and component-welding positions for a range of railway bogie welded joints. Prepared joints were then assessed for cracks and porosity defects. It was observed that an increase in welding speed resulted in an increase in crack and pore sizes. The same applied to increase in welding angle. Identified crack sizes ranged from 0.2 to 2.6 mm. Impact of such defects on fatigue life was assessed by evaluating the residual fatigue life of the component using the Paris law for stress amplitude of 150 MPa. The fatigue life of the bogie was estimated to be 6.23 × 10 5 instead of the required 1 × 10 6 cycles. It was concluded that manufacturing conditions have a significant effect on fatigue life of high strength steel welded joints. Travel speed and welding angle are critical.

Significant amounts of loose biomass are produced annually through agricultural and forestry acti... more Significant amounts of loose biomass are produced annually through agricultural and forestry activities. It is common practice to burn these loose biomass deliberately after harvesting or in accidental veld fires in the case of forestry. This energy could be harnessed for cooking and heating. The challenge with the use of loose biomass lies in its low density and hence low energy content which can be improved through densification. The aim of this paper is to determine the optimum densification parameters that can be used to develop manual briquetting technologies to empower poor communities to harness the energy available in loose biomass that they dispose annually. This forms part of a larger project aimed at developing off grid biomass value chain technologies. Using loose grass and loose leaves, experimental data revealed an optimum density of 1250 kg/m3 and a corresponding densification pressure of 40 MPa. In addition, a comparison of the thermal profile of solid round and round hollow briquettes showed more superior performance of the round hollow briquette based on recorded maximum combustion temperatures. Briquettes with a hole in the middle are therefore preferred to solid briquettes.

Displacement ventilation is a low-cost ventilation technique used in distributing conditioned air... more Displacement ventilation is a low-cost ventilation technique used in distributing conditioned air in Heating, Ventilation and Air Conditioning (HVAC) systems. This is a ventilation strategy well suited to significantly reduce building energy consumption in this age of high energy costs, global warming and climate change. This is achieved through the leveraging of natural buoyancy-driven flow in the conditioned space in a way that minimizes energy expenditure in supply and extraction fans. In addition, the conditioned air is supplied at higher temperature implying lower energy demand for cooling units. The global legislative move towards greener buildings demands the use of sustainable and energy efficient air conditioning systems of which displacement ventilation makes a major contribution. One of the challenges in using displacement ventilation is the stratified temperature distribution in the conditioned space. The temperature gradients between the ceiling and the floor can lead to decreased comfort conditions. One approach to overcome this problem is to use the chilled ceiling. How does one size the chilled ceiling system in such cases? The purpose of this paper is to present a detailed design analysis of a displacement ventilation chamber that includes chilled ceiling. The chamber utilizes an under floor air supply system into a conditioned space configured to represent typical office space. The construction and performance testing of the displacement ventilation testing chamber is then reported in a subsequent paper.

Composite materials have now attracted wide acceptance in product development and manufacture esp... more Composite materials have now attracted wide acceptance in product development and manufacture especially in automotive and aerospace applications where weight reduction and low fuel consumption are critical product performance metrics. In most applications, glass and carbon fibre composites are used. However, natural fibre composites also offer attractive properties. They are competitive especially in terms of price and density when compared to glass and carbon fibre composites while providing similar mechanical properties. Commonly available natural fibres include coir and sisal. Resin transfer moulding (RTM) process is also an established technique for manufacturing composites as it offers good surface finish and dimensional control. The aim of this paper is to investigate the effect of resin transfer rate on the performance of the product. Coir fibre / epoxy resin composites are prepared using RTM for differing resin transfer rates and fibre fraction for treated and untreated fibres. The results obtained indicate a slight reduction in performance with reduction in resin transfer rate. However, stiffness remained unaffected. Improvement in stiffness and strength with increasing volume fraction was reported which was in agreement with literature. However, the data exhibited an optimum fibre volume fraction of 30% beyond which performance deteriorated. This investigation indicates that further work is required to optimise the production of natural fibre composites using RTM.

Papers by Abdullah Kaymakci

2017 International Conference on the Industrial and Commercial Use of Energy (ICUE), 2017

The production of greenhouse gases (GHG) has led to the Earth's surface temperature increasin... more The production of greenhouse gases (GHG) has led to the Earth's surface temperature increasing by an average of 0.6°C in the 20th century. This is partly due to over reliance on fossil fuels. Human activities are estimated to account for about 69% of GHG emissions. There is now an urgent need for alternative fuels, especially renewables such as biomass, to mitigate this. In most of Sub-Saharan Africa, cooking is conducted in open fires using fire wood. This practice has poor health implications due to gases emitted largely due to incomplete combustion. The consequence is reduced mortality especially for women and children due to respiratory related diseases such as chronic obstruction pulmonary disease (COPD). The main aim of this work is to report on tests conducted on a low-cost biomass briquette domestic stove that was developed to improved biomass briquette combustion. Thermal efficiency, rate of heat loss and combustion effectiveness of the design was analysed as key performance variables of the stove. The goal was to develop a safe and reliable low-cost biomass briquette stove that will be used for domestic cooking in communities with low income streams. Stove geometry and temperatures at various points were identified as major contributors to stove effectiveness. During the investigation, controlled cooking test (CCT) method was used. Results showed good stove performance for typical cooking times.

Transactions of the Canadian Society for Mechanical Engineering, 2019

The effect of metal transfer modes on mechanical properties of welded 3CR12 stainless steel was i... more The effect of metal transfer modes on mechanical properties of welded 3CR12 stainless steel was investigated. This was achieved by butt welding 10 mm thick plates of 3CR12. The effect of the metal transfer modes on the microstructure and the mechanical properties of the 3CR12 steel was then investigated as it was hypothesized that the change in welding positions will affect the transfer modes partly because of gravity. The microscopic examination revealed that the substrate was characterized by dual phase microstructure. Using the spectroscopic examination results, the ferritic factor calculation had shown that the microstructure was expected to be ferritic–martensitic during air cooling process. The tensile strength and Charpy impact energy were measured to be 498 MPa and 102 J, respectively. The heat input in the material was observed to be greater than 1 kJ/mm, which is the limiting factor for grain growth. Grain growths were observed in the heat affected zone of the welded mater...

Procedia Manufacturing, 2017

P91 and 10CrMo9-10 creep resistant steels are critical to the performance of boiler tubes and pow... more P91 and 10CrMo9-10 creep resistant steels are critical to the performance of boiler tubes and power generating plants in general. Components made from these materials are mainly joined by welding. This paper reports on the comparative study of the effect of TIG and SMAW welding on the mechanical performance of P91 and 10CrMo9-10. TIG was used for root welding while SMAW was used for weld filling of V-butt joints. Specimens of the two alloys prepared using recommended welding procedures are evaluated using optical microscopy and Vickers micro hardness assessment. Some specimens were post weld heat treated while others were not. Post weld heat treated (PWHT) specimens exhibited similar properties as the corresponding base materials for both steels. TIG welding resulted in significant grain size reduction in both steels. PWHT produced more consistent grain structure, which is favorable.

Procedia Manufacturing, 2017

This paper presents a study on the influence of manufacturing conditions on the fatigue life of w... more This paper presents a study on the influence of manufacturing conditions on the fatigue life of welded joints of high strength steels P355NL-1 and P355NL-2. Welding conditions were varied by adjusting the welding parameters and component-welding positions for a range of railway bogie welded joints. Prepared joints were then assessed for cracks and porosity defects. It was observed that an increase in welding speed resulted in an increase in crack and pore sizes. The same applied to increase in welding angle. Identified crack sizes ranged from 0.2 to 2.6 mm. Impact of such defects on fatigue life was assessed by evaluating the residual fatigue life of the component using the Paris law for stress amplitude of 150 MPa. The fatigue life of the bogie was estimated to be 6.23 × 10 5 instead of the required 1 × 10 6 cycles. It was concluded that manufacturing conditions have a significant effect on fatigue life of high strength steel welded joints. Travel speed and welding angle are critical.

ASME 2018 Joint Rail Conference, 2018

ASME 2018 Joint Rail Conference, 2018

2017 International Conference on the Industrial and Commercial Use of Energy (ICUE), 2017

The production of greenhouse gases (GHG) has led to the Earth’s surface temperature increasing by... more The production of greenhouse gases (GHG) has led to the Earth’s surface temperature increasing by an average of 0.6oC in the 20th century. This is partly due to over reliance on fossil fuels. Human activities are estimated to account for about 69% of GHG emissions. There is now an urgent need for alternative fuels, especially renewables such as biomass, to mitigate this. In most of Sub-Saharan Africa, cooking is conducted in open fires using fire wood. This practice has poor health implications due to gases emitted largely due to incomplete combustion. The consequence is reduced mortality especially for women and children due to respiratory related diseases such as chronic obstruction pulmonary disease (COPD). The main aim of this work is to report on tests conducted on a low-cost biomass briquette domestic stove that was developed to improved biomass briquette combustion. Thermal efficiency, rate of heat loss and combustion effectiveness of the design was analysed as key performance variables of the stove. The goal was to develop a safe and reliable low-cost biomass briquette stove that will be used for domestic cooking in communities with low-income streams. Stove geometry and temperatures at various points were identified as major contributors to stove effectiveness. During the investigation, controlled cooking test (CCT) method was used. Results showed good stove performance for typical cooking times.

P91 and 10CrMo9-10 creep resistant steels are critical to the performance of boiler tubes and pow... more P91 and 10CrMo9-10 creep resistant steels are critical to the performance of boiler tubes and power generating plants in general. Components made from these materials are mainly joined by welding. This paper reports on the comparative study of the effect of TIG and SMAW welding on the mechanical performance of P91 and 10CrMo9-10. TIG was used for root welding while SMAW was used for weld filling of V-butt joints. Specimens of the two alloys prepared using recommended welding procedures are evaluated using optical microscopy and Vickers micro hardness assessment. Some specimens were post weld heat treated while others were not. Post weld heat treated (PWHT) specimens exhibited similar properties as the corresponding base materials for both steels. TIG welding resulted in significant grain size reduction in both steels. PWHT produced more consistent grain structure, which is favorable.

This paper presents a study on the influence of manufacturing conditions on the fatigue life of w... more This paper presents a study on the influence of manufacturing conditions on the fatigue life of welded joints of high strength steels P355NL-1 and P355NL-2. Welding conditions were varied by adjusting the welding parameters and component-welding positions for a range of railway bogie welded joints. Prepared joints were then assessed for cracks and porosity defects. It was observed that an increase in welding speed resulted in an increase in crack and pore sizes. The same applied to increase in welding angle. Identified crack sizes ranged from 0.2 to 2.6 mm. Impact of such defects on fatigue life was assessed by evaluating the residual fatigue life of the component using the Paris law for stress amplitude of 150 MPa. The fatigue life of the bogie was estimated to be 6.23 × 10 5 instead of the required 1 × 10 6 cycles. It was concluded that manufacturing conditions have a significant effect on fatigue life of high strength steel welded joints. Travel speed and welding angle are critical.

Significant amounts of loose biomass are produced annually through agricultural and forestry acti... more Significant amounts of loose biomass are produced annually through agricultural and forestry activities. It is common practice to burn these loose biomass deliberately after harvesting or in accidental veld fires in the case of forestry. This energy could be harnessed for cooking and heating. The challenge with the use of loose biomass lies in its low density and hence low energy content which can be improved through densification. The aim of this paper is to determine the optimum densification parameters that can be used to develop manual briquetting technologies to empower poor communities to harness the energy available in loose biomass that they dispose annually. This forms part of a larger project aimed at developing off grid biomass value chain technologies. Using loose grass and loose leaves, experimental data revealed an optimum density of 1250 kg/m3 and a corresponding densification pressure of 40 MPa. In addition, a comparison of the thermal profile of solid round and round hollow briquettes showed more superior performance of the round hollow briquette based on recorded maximum combustion temperatures. Briquettes with a hole in the middle are therefore preferred to solid briquettes.

Displacement ventilation is a low-cost ventilation technique used in distributing conditioned air... more Displacement ventilation is a low-cost ventilation technique used in distributing conditioned air in Heating, Ventilation and Air Conditioning (HVAC) systems. This is a ventilation strategy well suited to significantly reduce building energy consumption in this age of high energy costs, global warming and climate change. This is achieved through the leveraging of natural buoyancy-driven flow in the conditioned space in a way that minimizes energy expenditure in supply and extraction fans. In addition, the conditioned air is supplied at higher temperature implying lower energy demand for cooling units. The global legislative move towards greener buildings demands the use of sustainable and energy efficient air conditioning systems of which displacement ventilation makes a major contribution. One of the challenges in using displacement ventilation is the stratified temperature distribution in the conditioned space. The temperature gradients between the ceiling and the floor can lead to decreased comfort conditions. One approach to overcome this problem is to use the chilled ceiling. How does one size the chilled ceiling system in such cases? The purpose of this paper is to present a detailed design analysis of a displacement ventilation chamber that includes chilled ceiling. The chamber utilizes an under floor air supply system into a conditioned space configured to represent typical office space. The construction and performance testing of the displacement ventilation testing chamber is then reported in a subsequent paper.

Composite materials have now attracted wide acceptance in product development and manufacture esp... more Composite materials have now attracted wide acceptance in product development and manufacture especially in automotive and aerospace applications where weight reduction and low fuel consumption are critical product performance metrics. In most applications, glass and carbon fibre composites are used. However, natural fibre composites also offer attractive properties. They are competitive especially in terms of price and density when compared to glass and carbon fibre composites while providing similar mechanical properties. Commonly available natural fibres include coir and sisal. Resin transfer moulding (RTM) process is also an established technique for manufacturing composites as it offers good surface finish and dimensional control. The aim of this paper is to investigate the effect of resin transfer rate on the performance of the product. Coir fibre / epoxy resin composites are prepared using RTM for differing resin transfer rates and fibre fraction for treated and untreated fibres. The results obtained indicate a slight reduction in performance with reduction in resin transfer rate. However, stiffness remained unaffected. Improvement in stiffness and strength with increasing volume fraction was reported which was in agreement with literature. However, the data exhibited an optimum fibre volume fraction of 30% beyond which performance deteriorated. This investigation indicates that further work is required to optimise the production of natural fibre composites using RTM.

2017 International Conference on the Industrial and Commercial Use of Energy (ICUE), 2017

The production of greenhouse gases (GHG) has led to the Earth's surface temperature increasin... more The production of greenhouse gases (GHG) has led to the Earth's surface temperature increasing by an average of 0.6°C in the 20th century. This is partly due to over reliance on fossil fuels. Human activities are estimated to account for about 69% of GHG emissions. There is now an urgent need for alternative fuels, especially renewables such as biomass, to mitigate this. In most of Sub-Saharan Africa, cooking is conducted in open fires using fire wood. This practice has poor health implications due to gases emitted largely due to incomplete combustion. The consequence is reduced mortality especially for women and children due to respiratory related diseases such as chronic obstruction pulmonary disease (COPD). The main aim of this work is to report on tests conducted on a low-cost biomass briquette domestic stove that was developed to improved biomass briquette combustion. Thermal efficiency, rate of heat loss and combustion effectiveness of the design was analysed as key performance variables of the stove. The goal was to develop a safe and reliable low-cost biomass briquette stove that will be used for domestic cooking in communities with low income streams. Stove geometry and temperatures at various points were identified as major contributors to stove effectiveness. During the investigation, controlled cooking test (CCT) method was used. Results showed good stove performance for typical cooking times.

Transactions of the Canadian Society for Mechanical Engineering, 2019

The effect of metal transfer modes on mechanical properties of welded 3CR12 stainless steel was i... more The effect of metal transfer modes on mechanical properties of welded 3CR12 stainless steel was investigated. This was achieved by butt welding 10 mm thick plates of 3CR12. The effect of the metal transfer modes on the microstructure and the mechanical properties of the 3CR12 steel was then investigated as it was hypothesized that the change in welding positions will affect the transfer modes partly because of gravity. The microscopic examination revealed that the substrate was characterized by dual phase microstructure. Using the spectroscopic examination results, the ferritic factor calculation had shown that the microstructure was expected to be ferritic–martensitic during air cooling process. The tensile strength and Charpy impact energy were measured to be 498 MPa and 102 J, respectively. The heat input in the material was observed to be greater than 1 kJ/mm, which is the limiting factor for grain growth. Grain growths were observed in the heat affected zone of the welded mater...

Procedia Manufacturing, 2017

P91 and 10CrMo9-10 creep resistant steels are critical to the performance of boiler tubes and pow... more P91 and 10CrMo9-10 creep resistant steels are critical to the performance of boiler tubes and power generating plants in general. Components made from these materials are mainly joined by welding. This paper reports on the comparative study of the effect of TIG and SMAW welding on the mechanical performance of P91 and 10CrMo9-10. TIG was used for root welding while SMAW was used for weld filling of V-butt joints. Specimens of the two alloys prepared using recommended welding procedures are evaluated using optical microscopy and Vickers micro hardness assessment. Some specimens were post weld heat treated while others were not. Post weld heat treated (PWHT) specimens exhibited similar properties as the corresponding base materials for both steels. TIG welding resulted in significant grain size reduction in both steels. PWHT produced more consistent grain structure, which is favorable.

Procedia Manufacturing, 2017

This paper presents a study on the influence of manufacturing conditions on the fatigue life of w... more This paper presents a study on the influence of manufacturing conditions on the fatigue life of welded joints of high strength steels P355NL-1 and P355NL-2. Welding conditions were varied by adjusting the welding parameters and component-welding positions for a range of railway bogie welded joints. Prepared joints were then assessed for cracks and porosity defects. It was observed that an increase in welding speed resulted in an increase in crack and pore sizes. The same applied to increase in welding angle. Identified crack sizes ranged from 0.2 to 2.6 mm. Impact of such defects on fatigue life was assessed by evaluating the residual fatigue life of the component using the Paris law for stress amplitude of 150 MPa. The fatigue life of the bogie was estimated to be 6.23 × 10 5 instead of the required 1 × 10 6 cycles. It was concluded that manufacturing conditions have a significant effect on fatigue life of high strength steel welded joints. Travel speed and welding angle are critical.